For controlling engine power, an air flow meter is typically used to determine an appropriate amount of air flow in an electronically controlled fuel injection system in order to establish an ideal air-to-fuel ratio. The fuel injection system produces a signal, having an appropriate pulse width, by which a fuel injector is controlled so as to open and produce as nearly a perfect air-fuel mixture as possible. Electronically controlled fuel injection systems, such as that described in, for instance, Japanese Unexamined Patent Publication 63-4549, are generally provided with only one air flow meter.
Typical high power engines, having a large number of cylinders, require a large quantity of intake air at high engine power demands. When such a high power engine is controlled by an electronically controlled fuel injection system having only one air flow meter, the air flow meter must detect a wide range of intake air amounts. Under such conditions, the air flow meter has difficulty in making detections over the wide range of intake air amounts without a decrease in detecting accuracy.
High power engines of this kind are typically provided with the same number of independent intake manifolds, each having an air flow meter disposed therein, as there are groups of cylinders, so as to isolate the groups of cylinders from one another. In such a high power engine, since each air flow meter is required to detect, or cover, only a narrow range of intake air amounts, each air flow meter is, accordingly, capable of detecting the amount of incoming intake air with high accuracy. However, if one of these air flow meters is damaged, out of order, or otherwise faulty, the group of cylinders with the air flow meter which is at fault is brought into suspension. This results in the engine creating a pumping loss and, accordingly, brings on a great decrease in engine power.